Telegraph receivers



April 8, 1969 F. A. MOORE 3,437,754

TELEGRAPH RECEIVERS Filed May 19, 1965 FRA/Vk A. M0 011:

Horne y US. Cl. 178-33 Claims ABSTRACT OF THE DISCLOSURE A teleprinter selector mechanism in which there are four components specifically engaged in the mechanical translation and transfer of electrical signals under the con trol of receiver cams, a control cam and a solenoid. The mechanism includes a set of code bar setting members each normally retained in a rest position, indicative of a space element of a code combination, by a corresponding one of a like number of code levers. The code levers are acted on sequentially by corresponding ones of a like number of receiving cams, during reception of a code combination, to pivot each from a first position to a second position while retaining the corresponding code bar setting member in the position in which it is indicative of a space element. In the event that an element of the received combination is in the mark condition a code lever setting bar is acted on by a control cam and an interposer under the control of the receiver electromagnet to cause the corresponding code lever to move from the setting (second) position to a third position, which movement permits the corresponding code bar setting member to move from the rest position indicative of a space element to a position in which it is indicative of a mark element. On termination of reception of all the elements, the code bar setting members reside in positions representative of element conditions of the received code combination.

The invention relates to a selector mechanism wherein a plurality of members are set sequentially in respective alternative positions and there retained until the selection sequence is completed. The invention is especially, through not exclusively, useful in teleprinter and like apparatus where it is required that a plurality of code levers be appropriately positioned on receipt of a sequence of signals comprising a code combination corresponding to a character or functional instruction.

According to the present invention there is provided a selector mechanism including: a plurality of levers each arranged for rotation and for linear displacement between a first linear position and a second linear position; means for rotating each lever in turn to dwell one at a time in a setting position; a lever setting member actuation of which displaces any lever in the setting position from its first linear position to its second linear position; means for latching in its second linear position each lever so displaced; means for sensing the linear position of each lever; and means, when each lever has dwelt in turn in its setting position and its linear position has been sensed, for restoring all levers into their first linear positions for a further setting sequence.

As applied to a teleprinter the invention provides a teleprinter receiver selector mechanism including: a code lever for each code element, each code lever being mounted for rotation and also for linear displacement between respective mark and space linear positions; receiver cam means for rotating each lever one at a time in turn into and then out of a setting position; means responsive to the receipt of an element of a code signal for effecting 1: ite States Patent C Patented Apr. 8, 1969 the selection of mark or space position for the corresponding code lever during its period of dwell in its setting position; means for retaining each lever in its selected mark or space position after the said period of dwell; and means upon completion of a code combination for resetting the code levers for selection by a further code combination.

An embodiment of the invention will be described with reference to the accompanying drawing which shows a pictorial view of a teleprinter selector mechanism ac cording to the invention.

The selector mechanism includes a receiver cam shaft 1 on which there are mounted five receiver cams 2 and a timing cam 3. To each of the receiver cams there is a corresponding code lever 4 and a code bar setting member 5 which serves both as a sensing member sensing the linear position of the code lever and as a latch for the code lever.

The setting members 5 are mounted, by way of elongated slots 6 therein, on rods 7 which support them for movement in the directions indicated by the arrows A and B. Each of the setting members is urged to move, in the direction indicated by the arrow B, to bring a stepped portion 8 of the member into engagement with a tongue 9 extending from the upper end of its corresponding code lever 4. This urgence is effected by a tension spring 10 afiixed at one of its ends to a lug 11 extending upwardly from the setting member and at the other end to a rod 12 which is fixed to the receiver frame (not shown). Each setting member 5 has a tongue 13 depending therefrom for engagement with a pivot rod 14 fixed to the apparatus frame.

Each of the code levers 4 has a circular recess 15 in a portion of its upper end which permits the code lever to pivotally engage the pivot rod 14 under the urgence of a tension spring 16 aflixed at one end to a lug 17 extending from the side of the code lever and at the other end to the right hand end (as seen in the drawing) of the corresponding setting member 5.

Each code lever 4 is urged, by Way of a cam following portion 18 thereof, into engagement with the periphery of its corresponding receiver cam 2 by a tension spring 19. This tension spring is affixed at one end to the lower end of the "code lever 4 and at its other end to a rod 21 which is fixed to the receiver frame.

The timing cam 3 is arranged as it rotates to act on a reading lever 22 which is pivotably mounted on a spindle 23 fixed to the receiver frame. This lever 22 has a camfollowing arm 24, a step arm 25, and, extending laterally from the stop arm, a code lever setting bar 26. The camfollowing arm 24 is normally urged into engagement with the periphery of the timing cam 3 by a tension spring 27. This tension spring is aflixed, at one of its ends, to the stop arm 25 and, at its other end, to a pin 32 which is secured to the receiver frame.

The code lever setting bar 26 is arranged with respect to the code levers 4 in such a manner that it is enabled to engage eac-h code lever by way of a step 20 on the lower end portion thereof. An interposer 28 is operative, under the action of a receiver electro-magnet of a well-known type, to move from the position in which it is shown in full outline and representative of a code combination signal element in the space condition, to the position in which it is shown in dotted outline and representative of a code combination signal element in the mark condition. In the former position (space condition), the interposer 28 is in the path of a tongue 29, descending from the stop arm 25 of the lever 22, in such manner that any pivoting movement in the clockwise direction of lever 22 is arrested by engagement of the tongue 29 with the interposer 28. In the mark condition, the interposer is displaced sufficiently (dotted outline) to prevent engagement with the tongue 29.

A resetting arm 30 for the code bar setting members is arranged to engage these members by way of stepped portions 31 therein. The resetting arm 30 is actuated, for example by means (not shown) of a cam-following portion thereof and a cam on the receiver cam shaft 1, to cause it to move in each of the directions indicated by the arrows A and B once pre revolution of the shaft.

The operation of the mechanism illustrated will now be described. Let it be assumed that the mechanism is in its rest position with all the code setting bars 5 fully to the left as viewed in the drawing, all the code levers in their upper linear positions, and the timing cam 3 in a position such as shown with the cam-follower arm 24 against a riser of the cam. In order to show one of the code levers in its setting position, to be discussed below, but the rest of the mechanism in the rest position, the receiver cam shown on the left of the drawing has purposely been drawn in an angular position out of phase with its proper position with respect to the timing cam; with the timing cam 3 mounted on the same shaft 1 as the receiver cams 4, in practice, when the timing cam 3 is in the position shown, all of the code levers engage with the riser portions of their respective receiver cams.

The five code levers 4 correspond each to one of the code elements of a standard five-element code representative of a character or functional instruction. Each code element appears on the associated telegraph line as a mark" or a space signal. The normal teleprinter code is, however, in effect, a seven-element code, the first and last elements effecting start and stop, respectively.

Let it be assumed that the elements of a code combination of signals being received are sequentially markspace"space"-spacemark, together with the normal start and stop elements. On receipt of the start element the receiver cam shaft 1 is released, by wellknown means, to rotate through one revolution in the direction indicated by the arrow C. The resetting bar 30 is, in consequence, acted on to cause it to move in the direction indicated by the arrow B. This movement of the resetting bar 30 permits selected ones of the code bar setting members to be released, later on in the sequence of operations, for movement in the same direction B at appropriate times in the reception cycle of signal elements.

On the appearance, after the start element, of the first code combination signal element which is in this case in the mark condition, the cam shaft 1 has rotated by an angular amount sufficient to cause the first of the cams 2 thereon to act on the corresponding code lever 4. This code lever is therefore caused by its spring 19 to pivot in a clockwise direction about the axis of the rod 14, moving from its rest position into a setting position, as shown for the left hand code bar on the drawing. During this pivoting movement of the code lever 4 however, the corresponding code bar setting member 5 is maintained in its normal position of rest to the left. On termination of the pivoting movement of the code lever 4, the timing cam 3 acts on the reading lever 22 to permit it to pivot in a clockwise direction under the influence of the tension spring 27. Since the first element of the code combination is in the mark condition the inter poser 28 has been moved from the position in which it has been shown in full lines to the position shown in dotted outline. The lever 22 is thus unimpeded in its pivoting movement because the interposer 28 has been moved out of the path of the tongue 29 on the stop arm 25 of the lever. Continued pivoting movement of the lever 22 causes the code lever setting bar 26 to engage with the stepped portion 20 of the first code lever and to displace it downwards in the direction indicated by the arrow D, against the influence of the tension spring 16 particular thereto. By the time pivoting of the lever 22 has terminated, the setting bar 26 thereof has moved the code lever 4 downward by an amount which is sufficient to withdraw its tongue 9 clear otthe engaging step portion 8 of the corresponding code bar setting member 5.

In consequence this setting member is permitted to move in the direction indicated by the arrow B, under the in fiucnce of the tension spring 10 particular thereto, from its rest position to a position in which its tongue 13 engages with the rod 14. The code bar setting member has now sensed the mark position of its code bar and is itself in a position representative of the first mark element of the received code combination.

Continued rotation of the timing cam 3 causes the reading lever 22 to pivot in the anticlockwise direction to bring the code lever setting bar 26 out of engagement with the first of the code levers 4. This code lever however is retained in the downward position through engagement of the underside of the corresponding code bar setting member 5 with the upper end of the tongue 9. This code lever is thus latched by member 5 in the mark liner position. The receiver cam 2 associated with this first code lever has advanced so that the code lever is rotated out of the path of the setting bar 26.

On receipt of the second element of the code combination, which element is a space, the interposer 28 is caused to move back to the position in which it is shown in full lines to impede the reading lever 22 in its next pivoting movement in the clockwise direction.

By this time the cam shaft 1 has rotated by an angular amount sufiicient to cause the second one of the reading cams 2 to permit its corresponding code lever 4 to pivot, in its turn, into its setting position. The corresponding rotation of the timing cam would allow the reading lever 22 to pivot again were it not that, the received code element being a space, the lever 22 is arrested by engagement of the tongue 29 on its stop arm 25 with the interposer 28. The code lever setting bar 26 is thus prevented from engaging with the tongue 20 of the second of the code levers 4, which code bar thus remains in the linear position corresponding to space, and, after its period of dwell in the setting position is rotated out of the way of the code setting bar 26 for the remainder of the cycle of operations. The corresponding code bar setting member 5 continuous to remain in its rest position, and in which position it is representative of the second of the elements of the code combinations being in a space condition. Since the third and fourth elements of the code combination are in the space condition, the foregoingly described actions of the timing cam 3 and reading lever 22, and the corresponding receiver cams 2, code levers 4 and code bar resetting members 5 are repeated on reception of these elements.

On receipt of the fifth element of the code-a mark" the sequence of operations is similar to that described for the first code lever, only the fifth code lever being permitted by its receiver cam to enter the setting position for displacement by the setting bar 26.

In taking up positions representative of the elemments of a received code combination, the code bar setting members 5 may be employed to set code bars, of a well known arrangement thereof in a teleprinter, to positions in which they will act to cause a type head to be selectively positioned, or to select a type-lever to print a character, or perform a function represented by the received code combination. Alternatively the setting members 5 may be employed to perform a function, or to control an aggregate motion mechanism by which means a type-head is selectively positioned to print a character represented by the received code combination.

When all five of the code elements coresponding to a character or functional instruction have been received, the resetting arm 30 is moved back again in the direction of the arrow A, taking with it such of the code bar setting members 5 as are in the mark position and unlatching the corresponding code levers 4, which thus return, under the influence of their respective tension springs 16, to the space linear position. Thus all the code levers 4 and the code bar setting members 5 are returned to their rest positions in readiness for a further selection sequence. Finally, receipt of the stop element stops the cam shaft 1.

Although the invention has been described with reference to teleprinter operation, it will be evident that it may be employed in other apparatus where it is required selectively to set a plurality of members sequentially in respective positions and retain them there until the selection sequence is completed.

It is to be understood that the foregoing description of specific examples of this invention is made by way of example only and is not to be considered as a limitation on its scope.

I claim:

1. A teleprinter selector mechanism including:

a plurality of code bar setting members each arranged for linear displacement from a first to a second of two positions representative of respectively one or the other of two conditions of a corresponding element of a received corresponding code combination of signals;

a plurality of code levers each having a step portion, a cam following protrudence portion and a circular recessed portion with a tongue extension, said circular recessed portion normally retaining a corresponding code bar setting member in said first of the two positions;

a plurality of receiving cams each acting sequentially on said cam following protrudence of a corresponding code lever causing said lever to rotate from a first position to a setting position while retaining said corresponding code bar setting member in the said first of the two positions; and a code lever setting bar which in dependence on the received element being in the said other of the two conditions, causes said code lever in said setting position to be moved in a linear manner from said setting position to a third position in which the corresponding code bar setting member is permitted to take up said second of two positions, whereby on termination of the reception of all the elements of the code combination, the code bar setting members reside in positions representative of the conditions of the elements of the code combination.

2. A teleprinter receiver selector mechanism as claimed in claim 1 in which a resetting arm is provided operative on termination of the reception of said code combination of signals to move those of the code bar setting members residing in the second of the said two positions back to the said first position thereof.

3. A teleprinter receiver selector mechanism as claimed in claim 2 in which a setting bar common to all the code levers is operative to move a code lever from the said setting position to the said third position under the action of a timing cam rotated in synchronism with said plurality of receiver cams.

4. A teleprinter receiver selector mechanism as claimed in claim 3 in which an interposer is provided operative to take up one or the other of two positions in accordance with respectively the one or the other of the said two conditions of an element of a received code combination, and in which, when the element is in the said one condition, the interposer acts on the setting bar to prevent it from moving a corresponding one of the code levers from its said second position to its said third position.

5. A teleprinter receiver selector mechanism as claimed in claim 4 in which the interposer is arranged to take up the said one or the other of the two positions under the action of the teleprinter receiver electromagnet which electromagnet is responsive to electric signals representative of the condition of the elements of a received code combination.

References Cited UNITED STATES PATENTS 2,861,125 11/1958 Grifiith 178-33 2,879,333 3/1959 Boo l7833 3,274,338 9/1966 Clark l7833 THOMAS B. HABECKER, Primary Examiner. 

